Updates from the scientific community on planetary boundaries, global temperature, and sea level rise

31 January 2015

Photo credit: Stockholm Resilience Centre

Recent reports from some scientific organizations are indicating that human demands on the Earth are pushing the planet to the limit and that our subsequent responses – social, economic, political – need to adapt to these updated biophysical realities.

Planetary boundaries 2.0: Four out of nine crossed the safe threshold

The Stockholm Resilience Centre, with an international team of 18 experts led by Dr Will Steffen of the Climate Change Institute of the Australian National University, expanded the 2009 report they published about planetary boundaries and the need for a safe operating space for human use, and released their latest findings.

To quote, these key updates for Planetary boundaries 2.0 are:

“Four planetary processes are already entering the scientifically assessed global risk zone. Land use change is a new boundary that is estimated to be past the safe threshold, joining climate change, loss of biosphere integrity, and an overload in the nitrogen and phosphorus biogeochemical cycles.

“Regional hotspots have been mapped. Regional changes in several boundary processes, notably freshwater use and atmospheric aerosol loading may have global consequences if action is not taken to arrest the trends. This mapping also helps link local choices to global risks.

“Two boundary processes have been re-scoped and renamed. The updated Changes in biosphere integrity now focuses on the functions of ecosystems, as well as their biological biodiversity. Introduction of novel entities highlights the need to tackle environmental releases of toxic chemical pollutants, and also considers how other kinds of physical and biological interventions can have global impacts.”

Dr Rockström said that the “Earth is now in a quantifiably new state. We have identified nine boundaries. More worryingly, we assess Earth has now crossed four of these boundaries, including the two core boundaries, climate change and biosphere integrity. This means the two-degree climate target nations are set to agree on in Paris this year carries significant risks. We cannot rule out Earth crossing tipping points, for example, destabilising major ice sheets in Greenland and Antarctica, causing dramatic sea-level rise in the coming centuries. But we have also reached a tipping point for mobilisation. An increasing number of policymakers, businesses and NGOs all support immediate and profound action to decarbonise the global economy.”

Global temperature: 2014 as hottest year on record

Scientists from four major institutions that collect temperature data from different stations around the world each year and make judgments independently of each other released similar findings that 2014 is the warmest year on record since the late 1800s.

The Japan Meteorological Agency (JMA) released their data of last year and reported that “the annual anomaly of the global average surface temperature in 2014 (i.e. the average of the near-surface air temperature over land and the SST) was +0.27°C above the 1981-2010 average (+0.63°C above the 20th century average), and was the warmest since 1891. On a longer time scale, global average surface temperatures have risen at a rate of about 0.70°C per century.”

Photo credit: NOAA

Separate reports by the Goddard Institute for Space Studies-National Aeronautic and Space Administration (NASA) and the National Climatic Data Center-National Oceanic and Atmospheric Administration (NOAA), both in the United States, rank 2014 as Earth’s warmest since 1880. Both NASA and NOAA agree that the global average temperature increased about 1.4 degrees Fahrenheit (0.8 degrees Celsius) since 1880, with most of that warming occurring during the last three to four decades.

The HadCET or the Hadley Centre Central England Temperature dataset is the longest instrumental record of temperature in the world, where the mean, minimum and maximum datasets have been updated daily and monthly since 1878. The mean daily data series was started in 1772 and the mean monthly data in 1659.

Sea levels: Rising more sharply since the 1990s

Scientists from the Department of Earth and Planetary Sciences of Harvard University in the United States, led by Dr Carling Hay, also released their report “Probabilistic reanalysis of twentieth-century sea-level rise” in the 14 January 2015 issue of Nature where they freshly analyzed previous data on global mean sea level (GMSL) rise. Their analysis indicates that while sea level rise may have been overestimated by as much as 30% for most of the 20th century, the rate of acceleration since 1990 is much larger than previously thought.

Photo credit: un.org

Quoting from the abstract, “combining tide gauge records with physics-based and model-derived geometries of the various contributing signals, the analysis indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records. The increase in rate relative to the 1901-90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise.”

According to a report by Climate News Network that interviewed Dr Hay, “earlier estimates put mean sea level rise in the 20th century at between 1.5 and 1.8 millimetres a year. Dr Hay and her colleagues now think that, between 1901 and 1990, the true figure was probably closer to 1.2mm a year. But since 1990, global sea level has risen by 3mm a year on average. So, in fact, the acceleration since then has been faster than anybody expected – and this in turn could affect future projections.”

Global conversations and negotiations in 2015

One can say that even without scientific confirmation and validation, changes are being experienced in our climate and in our biophysical landscape that are challenging our capacities to respond and to adapt. But it is also clear that the forthcoming climate change negotiations in Paris in December 2015 need to listen to the scientific community, who also are aware that they need to communicate their findings in a way that will inspire change and action globally, locally, and individually.